The Radical Anions of [2.2]Paracyclophane-1,9-diene and Some of its Derivatives. An Unexpected Conformational Interconversion
作者:Jürg Bruhin、Fabian Gerson、Reinhart Möckel、Georges Plattner
DOI:10.1002/hlca.19850680212
日期:1985.3.27
temperatures, 2−· and 3−· gradually convert into the radical anions of [2.2]paracyclophane (1) and its 4,5,7,8-tetramethyl derivative, respectively. At higher temperatures, cleavage of one bridging chain in 2−· also occurs, with the formation of the radical anion of (E)-4,4′-dimethylstilbene (7). Both reactions of 2−· must involve the transient radical anion of [2.2]paracyclophane-1-ene (4) as proved by the observation
[2.2]对环phane -1,9-二烯(2)及其1,10,12,13,15,16-六氘代衍生物2 -D 6以及4,5,7,8的自由基阴离子-四甲基[2.2]对环-1,9-二烯(3)及其12,13,15,16-四氘代衍生物3 -D 4,已通过ESR光谱法进行了研究。对于偶合常数2 -在178 K·0.422是mT的四个当量烯属质子和0.046和0.020 mT的,每一个用于一组四个当量的芳族质子。这种超精细模式与带有两对等效质子的苯环中的任何一个都一致,并且表明预期的D 2 h降低了。对称。由于对两个耦合常数0.046和0.020 mT的调制,2 − ·的ESR光谱强烈依赖于温度。这些具有相反的符号,在273 K时平均为0.013 mT。实验结果以D 2 h对称性的过渡态,高于两个较低对称性的相互转化的等价构象33 kJ / mol的方式解释。一些证据表明件,这对称性d 2,即,在苯环2